The instant invention relates to the positioning of a fiber sliver end on a full flat can which is to be exchanged against an empty flat can after being filled on a draw frame.
The draw frame processes the fiber sliver and deposits the fiber sliver cycloidally in layers. When the flat can is full, it is replaced by an empty one. For this, the fiber sliver must be severed and the sliver end must be deposited against the can edge of the flat can.
If the severed fiber sliver end lies in a random position against the edge of the can it must be located by expensive, automatic devices and delays occur in positioning the flat can in the conveying system or machine for further processing. Finally, further processing is delayed.
In order to avoid these disadvantages, the utilization of a holding device to hold the fiber sliver in a defined position against the edge of the can is known. The holding device is installed as an addition on the edge of the can. The fiber sliver end must be deposited into this holding device. It is expensive to always use an additional holding system on the flat can and to design the edge of the can so that the holding device may be installed.
It is however not possible to do without positioning the fiber sliver end. This is a requirement for automation for subsequent operating steps in a spinning plant. With a constantly reproducible position of the sliver end in the can edge, it is possible to keep the expenses in subsequent operating phases or in piecing the fiber slivers to machines for further processing down or to reduce them.
If the fiber sliver end could be deposited at a constantly reproducible position on the can edge without requiring any additional holding system, this would contribute considerably to lowering the expense.
From this point of view, the German application P 43 24 948.5 succeeds in positioning the fiber sliver end without a holding system at the can edge in a reproducible manner. The positioning of the fiber sliver end on the flat can is achieved in that, starting from the stopped position of the flat can, the outlet of the rotary plate relative to the longitudinal axis of the flat can is positioned and stopped in such a manner that the fiber sliver loops are withdrawn in such manner when the flat can is displaced, that the fiber sliver comes to lie at the end of the displacement path in the central area of the forward face of the flat can and is then severed by a severing device. The filled flat can is standing in a stopped position beneath the rotary plate and is displaced from this position, and only then is the fiber sliver severed. As a result of the high degree of static friction of the fiber sliver, automatic unwinding of the fiber sliver loops may influence the unwound fiber sliver.
In another embodiment for the positioning of the fiber sliver, it is shown that following the positioning of the rotary plate outlet in a stopped position of the flat can, the fiber sliver is first severed between the pair of calendar rollers and the sliver guiding channel by means of a mechanical severing device. Following severing, the flat can is shifted into a transfer position. In this process, the severed sliver end is pulled out of the sliver guiding channel and hangs down on the forward face of the flat can at a positioned location and in suitable length. The fact that the positioning process requires a complete severing device of a known type is expensive. The severing device often has the disadvantage that the fiber sliver is deflected during the severing process and that the severed sliver end hangs down on the edge of the sliver guiding channel. This impedes the re-starting of the machine.